Dispersion-Compensated Microscope Objective Lens Design
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Solution Overview
Problem
Existing multiphoton excitation microscopes face challenges in dispersion compensation, particularly when using pulsed light with longer wavelengths, as it requires a large-sized dispersion compensation mechanism due to a smaller rate of change in refractive index with wavelength, leading to increased group delay dispersion and pulse width distortion.
Innovation Solution
The objective of the multiphoton excitation microscope includes an optical element as a light guide part, composed of a medium that satisfies the conditional expression 0.75 < θ2/θ1 < 1.33, where θ1 and θ2 represent ratios of refractive index changes between specific wavelengths, achieving an approximately linear relationship between wavelength and refractive index, thereby reducing group delay dispersion and eliminating distortion without the need for a large-sized dispersion compensation mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional objective with standard glass material is used, then the apparatus structure is simple, but the pulse width increases due to dispersion distortion when using pulsed light with longer wavelengths
Solution Approach 1:
The patent applies parameter changes by selecting glass materials with specific refractive index characteristics that satisfy the conditional expression 0.75 < θ2/θ1 < 1.33. This changes the optical parameters of the objective lens system to reduce group delay dispersion, thereby maintaining pulse width without requiring complex dispersion compensation mechanisms.
Solution Approach 2:
The patent converts the naturally occurring dispersion effect, which is typically harmful to pulsed light, into a beneficial outcome by carefully selecting glass materials whose dispersion characteristics match the conditional expression. This allows the dispersion to be minimized intrinsically rather than compensated for externally, maintaining pulse width while keeping the apparatus simple.
2Manufacturing precision
If a large-sized dispersion compensation mechanism is used, then the pulse width distortion is reduced, but the apparatus size increases
Solution Approach 1:
The patent extracts the dispersion compensation function from a separate large-sized mechanism and integrates it into the objective lens itself through careful selection of glass materials. The conditional expression 0.75 < θ2/θ1 < 1.33 ensures that the objective lens inherently provides the necessary dispersion compensation, eliminating the need for additional compensation mechanisms.
Solution Approach 2:
The patent merges the dispersion compensation function with the objective lens by selecting glass materials whose refractive index characteristics satisfy the conditional expression. This combines two functions (imaging and dispersion compensation) into a single component, reducing apparatus size while maintaining pulse width.
3Volume of moving object
If glass materials with small rate of change in refractive index are used, then the apparatus is compact, but the group delay dispersion increases causing pulse width distortion
Solution Approach 1:
The patent applies parameter changes by selecting glass materials with specific refractive index characteristics that satisfy the conditional expression 0.75 < θ2/θ1 < 1.33. This optimizes the balance between the rate of change of refractive index and dispersion characteristics, allowing compact apparatus design without pulse width distortion.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively reduces the amount of dispersion that needs to be compensated, allowing for efficient dispersion compensation and maintaining a compact apparatus size, even when using pulsed light in the infrared region, thereby improving the multiphoton excitation process by minimizing pulse width distortion.
Implementation Method 1
Pulsed light is dispersed when passing through a medium. In particular, if light components of different wavelengths within the pulsed light become different in velocity due to dispersion, this will result in a distorted light waveform
Implementation Method 2
The first optical element consists of a medium that satisfies the following conditional expression for θ1 and θ2: 0.75 < θ2/θ1 < 1.33, achieving an approximately linear relationship between wavelength and refractive index
Data Source
AI summary
An observation apparatus includes: alight source that emits pulsed light; and an objective that includes a first optical element serving as a light guide part and irradiates a sample with the pulsed light. The first optical element consists of a medium that satisfies the following conditional expression for θ1 and θ2:0.75<θ2/θ1<1.33where θ1=(n2−n1)/(λ2−λ1) and θ2=(n3−n2)/(λ3−λ2) are satisfied (λ1 indicates a light wavelength of 706.52 nm; λ2 indicates a light wavelength of 1529.6 nm; λ3 indicates a light wavelength of 2325.4 nm; and n1, n2, and n3 respectively indicate refractive indexes that the medium has for λ1, λ2, and λ3).